ce.ProtectedNode: Use surface initialize event instead of toolbarPosition

Follows-up 867ec44a9.

Because:
- #toolbarPosition is emitted more than once (so this
  should at least have been a once() bind, not a connect)
- It is emitted for more than 1 toolbar (includes context menu
  toolbar)
- Semantically incorrect (we want to know when the surface changes
  not the toolbar)
- We want to get rid of that event entirely and this is the last
  use of it.

Change-Id: Ica5ed04052f48fe84607abab72bcf65f97d689ed
Merge "ce.ProtectedNode: Use surface initialize event instead of toolbarPosition"